Bus bar for electrical power distribution

ABSTRACT

A bus bar for electric power distribution, comprising a body made of conducting material, the body having, on at least one side, at least one slot which has a C-shaped cross-section, the back wall of said C-shaped slot comprising two substantially straight portions which form an angle of less than 180° between them.

BACKGROUND OF THE INVENTION

The present invention relates to a bus bar for electrical powerdistribution having improved shape and characteristics.

More particularly, the bus bar according to the invention has astructure with a modular geometry in which the basic geometric elementcan be easily adopted to provide bus bars sized to carry nominalcurrents having different amperages; moreover, the bus bar according tothe invention is unique in its simplicity both from the point of view ofproduction and in practical use, allowing to considerably simplifyassembly.

It is known that distribution switchboards for distributing electricpower to a plurality of electrical devices, such as for example circuitbreakers, use a system of mutually parallel bus bars.

Each one of the bars is connected to a corresponding polarity of theelectric power supply mains; the connection between the bus bars and thedevices is provided by means of adapted conductors, such as for examplelaminae, which are shaped appropriately according to the type of device.

Bus bars, according to the functions that they are required to performin the practical application, must have a few basic characteristics; inparticular, they must have a simple and functional constructivestructure which allows extreme flexibility in assembly and coupling toother conducting or insulating elements. Said constructive structuremust also be conceived so that it can be easily adopted to produce barsthat conduct nominal currents with different amperages, without havingto significantly modify the steps of the production of said bars or ofthe elements to which they are to be coupled.

It is also important for the bars to have a structure which on the onehand ensures the rigidity required to withstand the electrodynamicstresses produced by the flow of current during normal conduction and onthe other hand allows to optimize the amount of material used inproduction, so as to achieve an economic benefit.

In the current state of the art, the use of conventional bus bars hasdrawbacks which make them less than satisfactory from the point of viewof production and in practical use.

It is traditionally known to use flat bars with a solid rectangulartransverse cross-section; although these bars are extremely simple fromthe point of view of production, they have considerable disadvantages incoupling to other elements, such as for example additional bars. Suchcases in fact require bar drilling operations, which vary in eachinstance according to the coupling configuration to be obtained, and theadoption of particular connecting means which are appropriately shaped.An example in this regard is shown in U.S. Pat. No. 5,364,203.

It is also known in the art to use bus bars whose transversecross-sections are shaped so as to facilitate coupling to other bars orto supporting and/or insulation elements; these elements are meant tofix the bars to supporting structures and to assist them in withstandingthe electrodynamic stresses. One of the shortcomings of conventionalshaped bars is the fact that as the amperage level of the nominalcurrents to be carried rises, the constructive structure of the bars isconsiderably modified; this in particular leads to the need tocorrespondingly modify the supporting and/or insulation elements thatcouple to the bars. Moreover, coupling between bars is provided by meansof conventional devices, for example connecting devices, which requirethe use of fixing means, typically T-shaped bolts. Said screws have ashaped head which, during assembly, is inserted in one of the slots ofthe bar and geometrically couples to the walls of said slot; however,this operation is difficult, because the screw does not stay in positionbut tends to fall, and therefore requires particular care on the part ofthe operator. In order to obviate this drawback, the solution used mostcommonly in the art is to associate with the head of the screw anadapted spring, for example a leaf spring, which is welded onto the heador otherwise locked onto the screw; although this solution is effectivefor the screw-bar coupling, it is disadvantageous because it requires anadditional constructive component and has a negative effect on costs.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a bus bar for electricalpower distribution whose structure has a modular geometry in which thebasic geometric element can be easily adopted with bars sized fornominal currents of different amperage, for example 400A rather than1600A, without significantly modifying the steps of the production ofthe bars or of the insulating and/or supporting elements that will becoupled to them, thus allowing advantageous economies of scale.

Within the scope of this aim, an object of the present invention is toprovide a bus bar for electric power distribution whose constructivestructure allows extreme flexibility and ease of execution in assembly.

Another object of the present invention is to provide a bus bar forelectric power distribution whose structure is provided by using anoptimum amount of material and at the same time has the rigiditysufficient to withstand the electrodynamic stresses to which it issubjected during normal operation.

Another object of the present invention is to provide a bus bar forelectric power distribution which is highly reliable, relatively easy tomanufacture and at competitive costs.

This aim, these objects and others which will become apparenthereinafter are achieved by a bus bar for electric power distribution,comprising a body made of conducting material, characterized in thatsaid body has, on at least one side, at least one slot having a C-shapedcross-section, the back wall of said C-shaped slot comprising twosubstantially straight portions which form an angle of less than 180°between them.

The bus bar according to the invention has the advantage of having astructure with a modular geometry whose basic geometric element issuitable to be easily implemented in the production of bus bars sizedfor nominal currents of different amperage, for example 400 A, 600 A,1000 A, 1600 A or others, without significantly modifying the steps ofthe production of the bars or of the supporting and/or insulationelements to which said bus bars couple.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention willbecome apparent from the following detailed description of preferred butnot exclusive embodiments of the bar according to the invention,illustrated by way of non-limitative example in the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of a first embodiment of the bus baraccording to the invention;

FIG. 2 is a plan view of the bar of FIG. 1;

FIG. 3 is a perspective view of a second embodiment of the bar accordingto the invention;

FIG. 4 is a plan view of the bar of FIG. 3;

FIG. 5 is a perspective view of a third embodiment of the bar accordingto the invention;

FIG. 6 is a plan view of the bar of FIG. 5;

FIG. 7 is a perspective view of a fourth embodiment of the bar accordingto the invention;

FIG. 8 is a plan view of the bar of FIG. 7;

FIG. 9 is a view of a bus bar according to the invention, coupled with asuitably configured T-shaped bolt.

FIG. 10 is a view of switchboard using the bus bar according to theinvention.

In the following description, identical reference numerals designateidentical or technically equivalent elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the above figures, the bus bar for electric powerdistribution according to the invention comprises a body 100 made ofconducting material, for example copper, which preferably has asubstantially quadrangular transverse cross-section. In particular, asshown in FIGS. 1-9, the body 100 has a rectangular transversecross-section; likewise, and in a fully equivalent manner, thetransverse cross-section might be square or trapezoidal or may have anyother shape, provided that it is adapted for the application.

As shown in detail in FIGS. 1 and 2, the body 100 has, on at least oneside, at least one slot having a C-shaped cross-section. Morepreferably, the body 100 has two C-shaped slots: a first slot 1, formedon a first side 10 of the body 100, and a second slot 2, formed on asecond side 20 of said body. The two sides 10 and 20 are alsosubstantially parallel to each other. Advantageously, the back wall ofeach one of the slots 1 and 2 comprises two substantially straightportions 7 and 8 which form an angle of less than 180° between them. Inparticular, the two portions 7 and 8 form between them an angle of 155°to 178°, preferably 160° to 175°, more preferably 165° to 172°. In theembodiments illustrated in FIGS. 1 to 8, the angle shown is ofapproximately 170°.

Therefore, the bar has a structure with a modular geometry in which thebasic geometric element, constituted by a C-shaped slot, can be easilyimplemented and replicated in the construction of bus bars sized tocarry nominal currents of different amperage. An example in this regardis shown in FIGS. 3 and 4, where three C-shaped slots are formed in thebody 100 of the bar: a first slot 1 and a second slot 2 are formed ontwo sides of the body 100, respectively 10 and 20, which aresubstantially parallel to each other, and a third slot 3 is insteadformed along a third side 30 of the body which is substantiallyperpendicular to the two sides 10 and 20. Said bus bar is preferablyadapted to carry nominal currents of 600 A, whereas the bus bar shown inFIGS. 1 and 2 is particularly adapted for conducting nominal currents of400 A.

Another possible embodiment of the bus bar according to the invention isshown in FIGS. 5 and 6, where on the body 100 there are five C-shapedslots: a first slot 1 and a second slot 4 are formed along a first side10 of the body and a third slot 2 and a fourth slot 5 are formed along asecond side 20 which is substantially parallel to the side 10. The fifthslot 3 is formed on a third side 30 which is substantially perpendicularto the sides 10 and 20. Said bar is particularly adapted for carryingnominal currents of 1600 A.

Yet another embodiment of the bus bar according to the invention,suitable for carrying nominal currents of 1000 A, is shown in FIGS. 7and 8. In this embodiment, the body 100 has six C-shaped slots: a firstslot 1 and a second slot 4 are formed along a first side 10 of the body100, a third slot 2 and a fourth slot 5 are formed along a second side20 of the body, with the sides 10 and 20 substantially parallel to eachother, and a fifth slot 3 and a sixth slot 6 are instead formed on athird side 30 and on a fourth side 40 respectively. The sides 30 and 40are substantially parallel to each other and substantially perpendicularto the sides 10 and 20.

Another advantageous aspect to be noted is the fact that when the busbars are connected to each other or to other coupling elements by way ofadapted connection and fixing means, the adoption of the C-shaped slotthus configured allows to simplify coupling and assembly. In particular,the bus bar according to the invention significantly facilitatesconnections by means of T-shaped bolts. As shown in FIG. 9, when the baris coupled with a T-shaped bolt, generally designated by the referencenumeral 200, the coupling between the two parts occurs mainly by meansof the interference that occurs between the two inclined planes 7 and 8that form the back wall of the C-shaped slot and the head plane 201 ofthe T-shaped bolt. Moreover, practical tests have shown that, though theextreme simplicity of this coupling, the interference between the walls7 and 8 and the head 201, assisted by the side contact that the internalwalls 11 and 12 of the slot give to the base of the head, is efficientto the point of allowing to place and automatically lock the bolt in thechosen position simply by way of its manual insertion and without usingadditional springs. Any further interference that occurs between theinternal side walls 13 and 14 of the C-shaped slot and the correspondingsurfaces of the head of the screw merely increases the effectiveness ofthe coupling.

In practice it has been observed that the bus bar according to theinvention fully achieves the intended aim and objects, since it has amodular structure with a basic geometric element which is adapted to beused to form bus bars sized for nominal currents of different amperage.Moreover, said structure, by way of the use of the slots configured asdescribed, facilitates assembly and allows to optimize the amount ofmaterial used while maintaining the structural rigidity characteristicsof said bar. The bar thus conceived, by way of its innovativecharacteristics, is particularly adapted for use in distributionswitchboards for low-voltage applications. Such switchboards comprise aplurality of electrical devices, such as circuit breakers and the like,which are electrically connected to corresponding bus bars, at least oneof which can be provided according to one of the above-describedembodiments.

The bus bar thus conceived is susceptible of numerous modifications andvariations, all of which are within the scope of the inventive concept;all the details may further be replaced with other technicallyequivalent elements.

In practice, the materials employed, so long as they are compatible withthe specific use, as well as the dimensions, may be any according torequirements and to the state of the art.

What is claimed is:
 1. A bus bar assembly system comprising a bus barfor electric power distribution, and connection and fixing means,wherein said bus bar comprises a body made of conducting material, saidbody having, on at least one side, at least one slot having a C-shapedcross-section, a back wall of said C-shaped slot comprising twosubstantially straight portions which form an angle of less than 180°between them, and wherein said connection and fixing means comprise aT-shaped bolt having a head inserted in said C-shaped slot, the couplingbetween said bolt and said bus bar occurring by means of theinterference between the head of the bolt and the substantially straightportions of the back wall of said C-shaped slot.
 2. The bus bar forelectric power distribution according to claim 1, wherein said body hasa substantially quadrangular transverse cross-section.
 3. The bus baraccording to claim 1, wherein said body has two C-shaped slots, a firstslot being formed on a first side of the body, a second slot beingformed on a second side of the body, the first and second sides beingsubstantially parallel to each other.
 4. The bus bar according to claim1, wherein said body has three C-shaped slots, a first slot and a secondslot being formed on two substantially parallel sides of the body, athird slot being formed along a third side of the body, said third sidebeing substantially perpendicular to said first and second sides.
 5. Thebus bar according to claim 1, wherein said body has five C-shaped slots,a first slot and a second slot being formed along a first side of thebody, a third slot and a fourth slot being formed along a second side ofthe body, said first and second sides being substantially parallel toeach other, a fifth slot being formed on a third side of the body whichis substantially perpendicular to said first and second sides.
 6. Thebus bar according to claim 1, wherein said body has six C-shaped slots,a first slot and a second slot being formed along a first side of thebody, a third slot and a fourth slot being formed along a second side ofthe body, said first and second sides being substantially parallel toeach other, a fifth slot and a sixth slot being formed respectively on athird side and on a fourth side, said third and fourth sides beingsubstantially parallel to each other and being perpendicular to thefirst side and to the second side.
 7. An electric power distributionswitchboard comprising a plurality of electrical devices, such ascircuit breakers and the like, which are electrically connected tocorresponding bus bars, wherein at least one of said bus bars comprisesa body made of conducting material, wherein said body has, on at leastone side, at least one slot having a C-shaped cross-section, a back wallof said C-shaped slot comprising two substantially straight portionswhich form an angle of less than 180° between them.
 8. The bus bar forelectric power distribution according to claim 1, wherein said twosubstantially straight portions form an angle comprised between 155° and178°.
 9. The bus bar for electric power distribution according to claim8, wherein said two substantially straight portions form an anglecomprised between 160° and 175°.
 10. The bus bar for electric powerdistribution according to claim 9, wherein said two substantiallystraight portions form an angle comprised between 165° and 172°.